27 August 2018

Emodin – a Natural Anthraquinone Derivative Occurred in Rhubarb

Natural toxin

Rhubarbs are among the most popular vegetables found at European consumer markets. The edible stalks are proceeded as a common food ingredient in kitchen, while the roots and rhizomes can be used for different medicinal purposes, eg. as as a purgative. The treatment is primarily attributed from the bioactive anthraquinones and their glycosides.

For those who love cooking, rhubarbs (Rheum rhabarbarum L.) are among the “must-haves” in their grocery shopping carts. The fleshy stalks of the vegetables have a strong tart taste, often used as an ingredient in many dishes, such as pies, crumbles, jams, drinks and such.

Structure of emodin. Click image for interactive 3D-model

The roots and rhizomes of rhubarbs also find their popularity in pharmaceutical industries as herbal medicine. Among the bioactive constituents isolated from the plants, Emodin (CAS 518-82-1) is a representative of the free anthraquinones found not only within the species but also in the as the roots and barks of other plants, such as buckthorn (Rhamnus cathartica L.), cascara (Rhamnus purshiana L.), senna and aloe. The molecule is based on the 9,10-anthraquinone skeleton and has a predicted LogP of 3.82 (ChemAxon), water solubility of 0.222 mg/mL (ALOGPS).

Emodin has been used as a traditional Asian medicine since 2,000 years ago for its anti-cancer and anti-inflammatory and anti-diabetic effects. Moreover, emodin imparts cathartic and laxative properties, in which sense are widely used as a therapeutic option to against constipation.

Despite from its pharmacological benefits, however, an increasing number of recent in vivo and in vitro studies asscociated emodin with dose-depended hepatic and renal toxicity and reproductive toxicity, the action mechanism still being under investigation.

Smiles: Cc1cc2c(c(c1)O)C(=O)c3c(cc(cc3O)O)C2=O


  • Dong X, Fu J, Yin X, Cao S, Li X, Lin L, Huyiligeqi, Ni J. Emodin: a review of its pharmacology, toxicity and pharmacokinetics. Phytotherapy Research. 2016 Aug;30(8):1207-18.
  • https://www.drugbank.ca/drugs/DB07715